(a) Field of the Invention
The present invention relates to a piezoelectric loudspeaker, and more particularly to an ultra-thin structure of a piezoelectric loudspeaker.
(b) Description of the Prior Art
A piezoelectric loudspeaker is also called a ceramic loudspeaker, and comprises an oscillator composed of a metal sheet and multiple layers of piezoelectric ceramic sheets. Alternating voltage is inputted to the oscillator, such that the oscillator can curve and oscillate. Longitudinal vibrator type, dual-state type, piezoelectric polymer type, and many other types of piezoelectric loudspeakers are known to have thin and small-sized characteristics.
The oscillator of a conventional piezoelectric loudspeaker is quite thin and usually applied to mobile phones or tablet personal computers. The flaky oscillator is connected with an essential electrical wire or signal line by welding, and then the oscillator is adhered to the circuit board of a mobile phone. The assembly and welding procedure are complicated, and the quality of weld will have a great effect on the sound produced. The inventor of the present invention has invented a piezoelectric loudspeaker as disclosed in U.S. Pat. No. 8,053,954 to overcome the aforesaid problems.
The piezoelectric oscillator as disclosed in U.S. Pat. No. 8,053,954 is composed of two sheets. A shock absorption member is provided at the middle of the oscillator close to a fixed end thereof. However, the amplitude of oscillation of a free end of the oscillator, opposite the fixed end, may be so large that the piezoelectric loudspeaker may have noises to influence the quality of the sound. Accordingly, the inventor of the present invention has devoted himself with his many years of practical experiences to solve these problems.